Pipes for Transcanada Corp.'s planned Keystone XL oil pipeline are stacked at a depot in Gascoyne, N.D. The House of Representatives approved the Keystone XL pipeline Friday; the Senate voted against it on Tuesday. Andrew Cullen/Reuters/Landov hide caption

itoggle caption Andrew Cullen/Reuters/Landov

GOP Rep. Bill Cassidy and Democratic Sen. Mary Landrieu face off in a Dec. 6 Senate runoff. Both are pushing for legislation approving the remaining leg of the Keystone XL pipeline between Alberta, Canada, and Steele City, Neb. Gerald Herbert/AP hide caption

itoggle caption Gerald Herbert/AP

Pipes for TransCanada's planned Keystone XL pipeline are stored in Gascoyne, N.D. The U.S. House has voted to approve the proposed project, which would allow crude oil to flow from Canada to the Gulf of Mexico. The Senate plans to vote Tuesday on legislation that would greenlight the project. Andrew Cullen/Reuters/Landov hide caption

itoggle caption Andrew Cullen/Reuters/Landov

U.S. Rep. Juan Vargas, D-Calif., speaks Wednesday as U.S. military veterans, service members and immigration reform advocates look on during a press conference urging President Obama to move forward with immigration reform at the U.S. Capitol in Washington. Saul Loeb/AFP/Getty Images hide caption

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Sen. Mary Landrieu, D-La., chair of the Senate energy committee, spoke Wednesday about getting congressional approval for the Canada-to-Texas Keystone XL pipeline. With her is Sen. Joe Manchin, D-W.Va., a member of the committee. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP

A TransCanada Keystone Pipeline pump station operates outside Steele City, Neb. The State Department is extending the review period for the pipeline, given ongoing litigation in Nebraska over the project. Lane Hickenbottom/Reuters /Landov hide caption

itoggle caption Lane Hickenbottom/Reuters /Landov

TransCanada President and CEO Russ Girling comments on the approval of the Keystone XL pipeline route through Nebraska during a January 2013 news conference in Calgary, Alberta. Todd Korol/Reuters/Landov hide caption

itoggle caption Todd Korol/Reuters/Landov

A 2012 photo shows sections of pipe on a neighboring property to Julia Trigg Crawford family farm in Sumner Texas, in the path of the Keystone pipeline. TransCanada said today that it is delivering oil through the Gulf Coast portion of its proposed Keystone XL pipeline, from a hub in Cushing, Okla., to Houston-area refineries. Tony Gutierrez/AP hide caption

itoggle caption Tony Gutierrez/AP

Daryl Hannah is handcuffed and arrested during the Keystone XL Pipeline Protest at Lafayette Park in Washington on Wednesday. Leigh Vogel/Getty Images hide caption

itoggle caption Leigh Vogel/Getty Images

President Obama announces support for building an oil pipeline from Oklahoma to Texas, Thursday in Cushing, Okla. Tom Pennington/Getty Images hide caption

itoggle caption Tom Pennington/Getty Images

Demonstrators march with a replica of a pipeline during a protest to demand a stop to the Keystone XL tar sands oil pipeline outside the White House last November. Evan Vucci/AP hide caption

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